You've just described how the Palouse Falls are not an example of incised meanders. It's an example of a young basalt flow disrupting previously incised meanders. You say that a lazy meandering river suddenly become a rushing rapids flowing as straight as a stick for four miles. What am I missing here? Even if you had any temporal constraints on when or how quickly the straight as a stick canyon was formed, it can't even remotely be considered a meander, incised or otherwiwse. You say the basalt cliffs near Palouse Falls have a curious tendency to make sharp, 90° turns. Meanders don't do this. A previously incised river flowing across jointed basalt does. It doesn't matter that it doesn't sound like uplift to you. And I don't think anyone suggests that these features take billions of years to form. In most cases river downcutting is able to keep pace with uplift. That's why incised meanders form. The Grand Canyon is thought to have been carved mostly in the 5 or 6 million years.

Stair-stepping topography is usually attributed to differential erosion. The Grand Canyon is a perfect example. It's the softer inter-flow deposits that erode easier and the lavas are resistant. But in the Columbia plateau it could be all lava with different degrees of resistance to erosion. An exception is both marine terraces and river terraces. Marine terraces form when uplift raises a wave-cut platform above sea level. River terraces form when uplift causes a stream to cut down into its own deposits while meandering across a flood plain. Repeated episodes of uplift can result in multiple levels of nested terraces, both river and marine. But those in the picture clearly are not terraces; the river is not cutting into its own deposits. Actually a small terrace can be seen in the bottom of the canyon next to the stream.

Hi EverybodySorry I didn't get back before now. I was off line for a while. I hate to hit and run but I can just make a few comments and then I have to go again. As for the ledges, differential resistance to erosion is usually offered as the explanation. It is far easier to demonstrate than differential rates of uplift. Almost all rocks have differing resistance to erosion, and over time it doesn't take much of a difference in hardness for one rock to "win the race" of erosion. If the upper unit erodes faster it forms a ledge. If the lower one erodes faster it undermines the upper and a tallus would probably form. Rates of uplift are more difficult to establish. And it depends on what time scale you want to consider. On the finest scale all uplift is episodic, resulting from individual earthquakes. Sorry, gotta go now.

I think the more sophistocated YECs, if there is such a thing, or at least the most modern and up to date YECs, actually think the earth was flat, or with very low relief prior to the flood. Most now subscribe to some kind of catastrophic or rapid plate tectonics in which the present day mountains were formed. They realized that instead of beating their heads against the overwhelming evidence in favor of plate tectonics, it is more in their interest to embrace it. That way they can account for all the evidence in favor of plate tectonics, claim that it is consistant with their flood model, and not need any more water than is presently on the planet. The only problem is cramming all of geologic history, all the tectonic movement on every fault in the world, into the flood year. But if you can think that the oceans covered Mt. everest, why not.

Frictional heating is a huge problem for rapid plate tectonics. No doubt movement along thousands of individual faults and fractures that contributed the Uplift of Mt Everest and the Himallayas, probably millions of seismic events. When you've got 20 million years to accomplish the uplift it's no problem but if all that movement happens in one year, the problem is no longer "where did the water go?", it's "where did the energy go?" If all the crustal movements evident in the geologic record occurred in a short time you would expect widespread frictional melting, which is actually not all that common in the geological record.